Coco mats are made from the fiber between the outer husk and the meat of a coconut, called coir. The coir is then made into fibrous mats that are usable in hanging flower pots in much the same way sphagnum moss mats are used. Coco mats help hold the flowers and soil in place when you use basket-style planters that have large openings in the sides. You can also plant into the sides of the mat so that your flower arrangement surrounds the entire outside of the planter.
Fill a bucket with warm water. Place the coco liner inside the water and soak it for two to four hours. Pre-moistening the liner makes it easier to work with and keeps it from soaking up all the moisture from the soil once it is added.
Place the liner inside the planter. Mold it to the inside of the planter so the top edge of the liner is even with the rim. It may also protrude above the planter rim but by no more than 1 inch.
Cut small slits in the liner if you are planting the flowers on the outside of a basket-liner planter as well as in the soil on top of the planter. Space slits at least 3 inches apart.
Remove flower transplants from their nursery pots and feed their roots through the slits in the coco mat so the flowers are on the outside of the basket and the roots are on the inside. Fill the planter with potting mix, firming it gently around the roots of each plant to hold them in place. Add soil until it is within 2 inches of the rim of the planter.
Plant flowers in the top of the planter as you would in any traditional flower pot. Plant flowers to the same depth they were at in their nursery pots and space them 3 to 5 inches apart.
Water thoroughly after planting so that the soil is evenly moist throughout.